Are you making a starter with a stir plate? This stir bar will help to keep your starter constantly oxygenated so that you can grow strong, healthy cultures of yeast to pitch. This stir bar measures 25 x 7 mm and is perfect for starters in 1000 ml flasks. Stir bars can be boiled in the flask along with the starter wort and should be added to the flask when you're propagating yeast on a stir plate. These stir bars are magnetized so that the magnets in stir plates will grab the magnet and spin it, creating a vortex that oxygenates your starter. Even if you already have one, an extra stir bar is always good to have in hand on case one accidentally slips down the drain or into the fermenter.